1. Technical Field
This invention relates to a method of sputtering and a device for sputtering, which is constituted of at least a substrate and a target for forming a thin film on the substrate. Ionized gas is smashed up to the target and atoms and/or molecules emitted from the target adhere to the substrate to form the thin film thereon.
2. Description of the Related Art
JP 11-335835 A discloses a sputtering device in which, in order to improve the evenness of a film's thickness, a disc-shaped target and a substrate on which a film is formed are provided so as to face each other, and the substrate rotates while revolving on the target. The substrate is rotated so as to change an area overlapped between the target and itself from the last overlapped area. In the sputtering device disclosed in this reference, the target is larger than the substrate in order to improve the evenness of the film's thickness on the substrate. In the case that concavities and convexities exist on the substrate, the thickness of the film formed in the concavity is not even, so that a problem such as worse coverage distribution arises.
JP 2001-262336 A discloses a sputtering device in which, in order to ensure evenness of a film's thickness over a wide range of a large-sized substrate, impedance of a second adjustment circuit is adjusted so as to bring a direct-current component of a potential of a substrate holder close to an electrical potential of plasma to form a thin film of an insulator. In this device, a specific angle is formed between the target and a surface of the substrate holder, and a center of the target is not identified with a center of the substrate holder. In the sputtering device disclosed in this reference, because a distance between a surface of the substrate and the target is inhomogeneous, even if the substrate is revolved and rotated, operation for a potential difference between a cathode and the target and/or operation for an impedance of the adjustment circuit must be strictly controlled. Therefore, a problem such as complex operation arises.
JP 2002-20864 A discloses a sputtering device in which a substrate and a target are located so as to rush (emit) the sputtered particles to the substrate, and the substrate is rotated so that a magnetic film with a high anisotropic rate can be formed uniformly. In the sputtering device disclosed in this reference, because materials emitted from the target are restricted by a plate for modifying distribution, a thin film can be formed on the substrate. However, a problem such as availability of the target being very inefficient arises. Besides, there is a problem in that the film is thicker in a center portion of the substrate because the center portion thereof is a common portion in every target.
JP 2002-20866 A discloses that, in a sputtering device which sputters to an object by generating a magnetic field on a target and applying an electric field to the target, a means for generating the magnetic field is located adjacent to the target and comprises a plurality of magnets which rotate complexly so as to combine rotation and revolution. In the sputtering device disclosed in this reference, the plural magnets located at the back of the target are rotated complexly (i.e., in a complex manner) to change the magnetic field complexly. However, the complex change of the magnetic field makes electrons moving like a cyclone on the target work in a complex manner, so that the magnetic field and the electric field are not certain. As a result, an erosion extent on the target causes evenness, but smashing directions of atoms from the target are not uniform, and a problem such that distribution of the film's thickness and coverage distribution of the substrate are not uniform arises.